Samples of biological or pharmaceutical materials to be recovered, for example during drug discovery experiments, are often contained in a liquid or solvent vehicle. In order to recover the sample, it is necessary to dry the specimen. Thus, it is known to place the specimen in a vessel, such as a test tube, and to utilize a device known as a vacuum concentrator to dry and recover the sample. Vacuum concentrators subject the specimens to centrifugal forces in order to apply the specimen against the end of its container. The evaporation process is accelerated by creating a partial vacuum in the chamber, thereby lowering the boiling point of the liquid or solvent vehicle. In addition, the specimens may be heated to further facilitate the drying process. The centrifugal forces inhibit splashing in the event the specimens boil.
Extant vacuum concentrators often simply execute a pre-determined program. That is, the specimens are centrifuged and heated under partial vacuum for a particular amount of time intended to be sufficient to complete the drying process. Since these programs do not take into account the actual amount of solvent remaining in the specimens, they may result in shorter- or longer-than-necessary vacuum concentrator runs. Thus, the result may be insufficient drying, in the event of a program run shorter than required, or inefficiency, in the event of a program run longer than actually required.
Accordingly, it is desirable to provide a method of accurately determining the end of a run in a vacuum concentrator. That is, it is desirable to provide a method for accurately determining when all solvents have been evaporated from the specimens being dried in a vacuum concentrator.